As shown in FIG. 1, a modern golf ball 100 generally includes multiple layers, including an outer layer 102 called a “cover” and an inner body 104 called a “core.” Many modern golf balls also have at least one additional layer, called a “mantle” 106, situated concentrically outside the core 104. The cover 102 is typically formed around the mantle 106 so that the cover is generally concentric with the mantle and the mantle and core are sealed inside the cover. For purposes of description herein, the term “core” is used generally herein to denote the portion of a golf ball located inside the cover and providing the surface on which the cover is formed, regardless of whether the core comprises one or more layers.
Conventional techniques used for forming the cover include casting, compression molding, and injection molding. Casting (also called “cast-molding”) is performed in a ball cavity formed by bringing together two mold halves that define respective hemispherical cavities. Casting is especially suitable for forming the cover of a thermoset material. A precise amount of liquid thermoset resin is introduced into the hemispherical cavities and partially cured (“gelled”). The core is placed in the hemispherical cavity of one mold half and supported by the partially cured resin. The second mold half is placed relative to the first mold half to enclose the core and resin in the resulting ball cavity. As the mold halves are brought together, the resin flows around the core and forms the cover. The mold body is heated briefly to cure the resin, and then cooled for removal of the ball from the mold body. Advantages of casting are that it achieves substantial uniformity of cover thickness without having to use centering pins, and it can be performed at a much lower pressure inside the mold than injection molding or compression molding.
Conventional casting techniques require discontinuous “stop-and-go” type actions to dispense material, insert cores/mantles into mold halves, and to assemble the mold and disassembly the molds to manufacture golf balls. It is desirable to provide improved casting methods and systems that provide a more continuous casting process to reduce delays associated with the discontinuous processes of the conventional systems.